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IB Biology HLC1.2 Cell respirationQuestion Bank

C1.2 Cell respiration

Question 1

[Maximum number: 2]

Arabidopsis is a small flowering plant in the mustard family (Brassicaceae) that is widely used in basic research. It has a short life cycle, flowers quickly producing a large number of seeds and is easy to cultivate. It forms a circle of leaves known as a rosette that lies close to the soil. Flowers form at the end of short stems.

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A study was carried out of differences in development between Arabidopsis plants grown in long days ( 16 hours light, 8 hours dark) or short days ( 8 hours light, 16 hours dark). The sixth leaf (L6) to emerge in the rosette of each plant was used in all investigations.

New leaves are initiated by the meristem and go through four stages as they develop.
- Stage 1 (S1) - rapid cell division
- Stage 2 (S2) - cell division has ceased, cell expansion continues
- Stage 3 (S3) - decreasing cell expansion rate
- Stage 4 (S4) - leaf growth complete

The start of each stage of leaf development for plants grown in long days and short days is shown above the first graph.

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Question 1(c)

(a)

Leaves were removed from Arabidopsis plants that had been grown in long day and short day conditions and the concentration of starch within them was measured. This was done both at the end of the day (D) and at the end of the night (N) in each of the four stages of development (S1, S2, S3, S4).

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Discuss the evidence provided in the bar chart for the hypothesis that plant leaves use up starch reserves for cell respiration during the night.

[ 2 ]

Question 1

[Maximum number: 5]

Mammalian tissues use circulating nutrients including glucose, amino acids and various intermediate metabolites for respiration. The concentration in the blood of glucose and other metabolites is regulated as a part of homeostasis. The concentration of a metabolite remains constant if it is absorbed from arterial blood and consumed by metabolism at the same rate as it is produced by metabolism and released into venous blood.

Circulatory turnover flux ( Fcirc F_{\text {circ }} ) is the rate at which a metabolite in the blood is both consumed and produced, with the concentration in the blood remaining constant.

Circulatory turnover fluxes were measured in fasting mice that had not fed for 8 hours. The table shows data for metabolites that had the highest circulatory turnover fluxes. Alanine, glutamine and glycine are amino acids.

Table

Question 1(g)

(a)

The brain is unlike other organs in its use of metabolites for the Krebs cycle.

Distinguish between the data for the brain and all the other organs and tissues.

[ 2 ]

Question 1(h)

(b)

Using any of the data in question 1, evaluate the hypothesis that the main metabolite absorbed by cells and used in respiration is glucose.

[ 3 ]

Question 5

[Maximum number: 1]

The diagram shows the chemical reaction that occurs during the last step of anaerobic respiration in human skeletal muscle cells.

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What is the purpose of this reaction?

A

To allow the release of energy from glucose breakdown to continue

B

To establish a concentration gradient of hydrogen ions for adenosine triphosphate (ATP) synthesis

C

To provide electrons for the electron transport chain

D

To reduce carbon compounds in the absence of oxygen

Question 6

[Maximum number: 1]

The diagram shows a simple respirometer used to measure the rate of respiration. Soda lime is used to absorb carbon dioxide.

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Which way will the drop of liquid move if the organisms are respiring aerobically?

A

The drop of liquid will not move as the volume of oxygen used in respiration equals the volume of carbon dioxide produced.

B

The drop of liquid will move left as oxygen is used up by the respiring organisms.

C

The drop of liquid will move right as carbon dioxide is produced by respiring organisms.

D

The drop of liquid will move right as carbon dioxide is produced and then left as oxygen is consumed.

Question 7

[Maximum number: 1]

Which of the following statements describes part of the Krebs cycle?

A

Reduced NAD is converted back to NAD.

B

A 4-carbon citrate binds with acetyl-CoA to form a 6-carbon intermediate.

C

Two decarboxylation reactions occur.

D

One ATP molecule is used in one stage of the cycle.

Question 7

[Maximum number: 1]

What is formed from glucose during anaerobic cell respiration?

A

Lactate and ATP in cytoplasm

B

Carbon dioxide and water in mitochondria

C

Lactate and carbon dioxide in mitochondria

D

Carbon dioxide and water in cytoplasm

Question 7

[Maximum number: 1]

What occurs during the stages of respiration?

Stage of respiration

Decarboxylation

Reduced NAD produced

Glycolysis

No

No

Link reaction

Yes

No

Krebs cycle

Yes

Yes

Electron transport chain

No

Yes

Question 8

[Maximum number: 1]

Students prepared respirometers in order to investigate respiration rates in seeds.

Respirometer 1

diagram not to scale

diagram not to scale

Respirometer 2

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How would the results differ in the respirometers after 30 minutes?

Respirometer 1

Respirometer 2

Oil drop does not move

Oil drop moves left

Oil drop does not move

Oil drop moves right

Oil drop moves left

Oil drop moves right

Oil drop moves left

Oil drop does not move

Question 8

[Maximum number: 1]

The diagram shows a respirometer used to measure respiration rate in germinating seeds.

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What is the expected direction of movement of the fluid at X and the function of the fluid at Y ?

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Question 8

[Maximum number: 1]

The graph shows the changes in lactate measured in an athlete's blood during exercise.

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Which hypothesis provides the most likely explanation for the curve?

A

As exercise intensity increases, lactate is converted back to glucose.

B

Anaerobic exercise results in high levels of lactate.

C

Lactate provides energy for intense exercise.

D

Under anaerobic conditions the body produces less lactate.

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